Chapter 26 Cosmology - PowerPoint PPT Presentation

Chapter 26 Cosmology. Units of Chapter 26. 26.1 The Universe on the Largest Scales 26.2 The Expanding Universe 26.3 The Fate of the Cosmos 26.4 The Geometry of Space Curved Space 26.5 Will the Universe Expand Forever? Einstein and the Cosmological Constant.

Copyright Complaint Adult Content Flag as Inappropriate

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

PowerPoint Slideshow about ' Chapter 26 Cosmology' - corin

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

The answer to this question lies in the actual density of the Universe.

Measurements of luminous matter suggest that the actual density is only a few percent of the critical density.

But, we know there must be large amounts of dark matter.

However, the best estimates for the amount of dark matter needed to bind galaxies in clusters, and to explain gravitational lensing, still only bring the observed density up to about 0.3 times the critical density, and it seems very unlikely that there could be enough dark matter to make the density critical.

If the expansion of the Universe is decelerating, as it would be if gravity were the only force acting, the farthest galaxies had a more rapid recessional speed in the past, and will appear as though they were receding faster than Hubble’s law would predict.

Discovery 26-2: correspond not to a decelerating universe, but to an accelerating one.Einstein and the Cosmological Constant

The cosmological constant (vacuum energy) was originally introduced by Einstein to prevent general relativity from predicting that a static universe (then thought to be the case) would collapse. When the universe turned out to be expanding, Einstein removed the constant from his theory, calling it the biggest blunder of his career.

Discovery 26-2: correspond not to a decelerating universe, but to an accelerating one.Einstein and the Cosmological Constant

Now, it seems as though something like a cosmological constant may be necessary to explain the accelerating universe—theoretical work is still at a very early stage, though!